The heights given in the trial record are sometimes in metric and sometimes in pieds, pouces. Accuracy of measurement probably varied.
My old French dictionary gives chatain as being brown hair and chatain-clair as light brown. A quick look through the interrogations shows that quite a few were described as chatain, chatain-clair or chatain-fonce which, unless one postulates a conspiracy of red-haired men, suggests it was the more commonplace colour.
Witnesses seldom mentioned hair colour, which is the first thing we would mention today, they were far more concerned with height and occasionally with build. Georges was 'bien-ventru' and the judge identified him as 'tres-gros'. He obviously hadn't been taking part in the exercises at that training-camp!
This suggests that Georges was a fat man of middle-height with light brown hair.
I think 'chatain' is more specifically translated as 'chestnut' (la châtaigne) which would put it more in the ginger-sandy spectrum.
I suspect 'Georges' was too busy eating diners in London to partake of assault courses.. Still, he was fit enough to get up that cliff at Biville!